Gas heat exchanger



Dec. 27, 1949 A. LENNING GAS HEAT EXCHANGER Fi1e1 July 15, 1946 ATTORNEYS Patented Dec. 27,1949

GAS HEAT EXCHANGER Alvar Lcnning, Stockholm, Sweden, assignor to Bolinders Fabriks Aktiebolag, Kallhall, Sweden,

a corporation of Sweden Application July 15, 1946, Serial No. 683,716 In Sweden July 31,1945

In continuously operating absorption type refrigerating systems employing an inert gas, the gas heat exchanger has to fulfil a very important function. The circulating gas is in a cold state when it is leaving the evaporator and inv a Warm state when it is leaving the absorber. In air-cooled systems, the heat quantities exchanged in the gas heat exchanger are frequently considerably greater than the net refrigerative capacity. Due to this fact, an air-cooled refrigerating system must necessarily be provided with a gas heat exchanger, and it also follows that the efliciency of such a heat exchanger should be as high as possible, while, at the same time, the dimensions of the heat exchanger for constructional reasons should be kept within narrow limits.

As a rule, heat exchangers are devised in the form of tubular exchangers. In such constructions, the inner diameter of the tubes should amount to at least one quarter of an inch, in order to prevent clogging. The resistance to flow in the heat exchanger frequently cannot be given such a high value as would be desirable with respect to the optimum resistance in the circulating portion of the system.

It has been previously suggested to devise a gas heat exchanger in the form illustrated in Fig. 1, according to which the exchanger consists of two tube-halves l and 2 having arranged therebetween a sealing partition 4 provided with longitudinal ribs or fin plates 3. With this construction, it is possible to adapt the heat transferring surfaces to the resistance to flow and to reduce the risk of clogging. From the point of view of manufacture it is, however, difiicult to produce a partition having the profile illustrated. In addition thereto, there arises the inconvenience that the longitudinal ribs also will transmit heat in the longitudinal direction of the exchanger with the result of a decrease in the efilciency thereof.

The present invention relates to a gas heat exchanger for absorption type refrigerating systems of the kind employing an insert gas, consisting of a substantially horizontal tube having a substantially horizontal inside sealing partition provided with ribs or fin plates. The invention has for its primary object to provide a heat exchanger of the type referred to which is simple in manufacture and works with high efficiency and thus avoids the above named inconveniences adherent to known constructions.

The invention will be described more in detail hereinbelow with reference to several embodiments thereof illustrated in the accompanying drawing.

2 Claims. (01. 257-262) Fig. 2 is a cross-sectional view, taken along the line IIII in Fig. 3, of a gas heat exchanger devised in accordance with the invention; Fig. 3 is a plan view of the exchanger, the upper half of the tube being removed. Figs. 4 and 5 show in a similar manner a slightly modified construction; and Fig. 6 is a cross-sectional view of a third embodiment.

Referring to Fig. 2, the tube of the heat exchanger consists of two halves l and 2 having arranged therebetweena sealing partition 4, the parts named being welded to each other in a similar manner as in Fig. 1. The partition is on both sides provided with triangularly shaped ribs or fin plates 5 extending obliquely with respect to the direction of flow of the gases and disposed substantially at right angles to the partition. The ribs constitute the legs of thin U-shaped plates which at their bases 6 are metallically connected with the partition. Due to this arrangement, the heat transferring capacity in the longitudinal direction of the tube is considerably reduced as compared with the construction shown in Fig. 1. Further, the obliquely arranged ribs will cause an effective turbulence of the gases, thereby increasing the heat transmission between the warm and cold sections of the heat exchanger. It is also possible to dimension the areas of the ribs such as to obtain the optimum resistance to circulation through the heat exchanger without any risk of capillary clogging.

According to the embodiment illustrated in Figs. 4 and 5, the ribs are divided into two portions 1 and 8 which are staggered in the longitudinal direction of the tube. As will be evident, a still more effective turbulence of the gas is obtained by this construction in which the resistance to flow can be varied to a great extent.

In a horizontal gas heat exchanger, the rich and cold gas flowing from the evaporator to the absorber should be conducted through the upper passage 9, whereas the weak and warm gas returning to the evaporator should flow through the lower passage [0. If, for instance, ammonia circulating in a closed system is used as the cooling agent in a refrigerating system including the gas heat exchanger, liquid ammonia is evaporated in the evaporator by the weak and warm gas flowing through passage ID. The gas cooled due to the evaporation is enriched with the evaporated ammonia and flows through passage 9 from the evaporator to the absorber. If not the entire amount of ammonia has been evaporated, liquid ammonia may enter the gas heat exchanger together with the rich and cold gas. If said rich gas is conducted through the upper passage 9, as indicated above, the metallic heat transmission path from the evaporating ammonia which may flow on the partition, to the ribs in the path of the warm gas becomes as short as possible so as to insure complete evaporation. As shown in Fig. 6, it is further advantageous to have the partition H slightly sloping downwards against its central portion such that the upper side of the partition forms a shallow channel for the ammonia. Otherwise, the ammonia would tend to flow along one of the corners between the tube and the partition with the result of reduced rate of evaporation. By means of the construction described, the flow of ammonia will be maintained in the central position, and, consequently, the generated cold can more effectively be utilized for decreasing the temperature of the weak warm gas flowing through the lower passage Ill.

The invention is obviously not limited to the embodiments thereof described by way of example. 1

What I claim is:

1. A gas heat exchanger for absorption type refrigerating systems of the kind employing an inert gas, comprising a substantially horizontal tube, a substantially horizontal partition for dividing said tube into a passage for rich gas and a passage for weak gas, and U-shaped plates located obliquely with respect to the axis of said 4 tube, the bases of said plates being secured to said partition, and the legs of said plates forming substantially triangularly shaped heat transmitting ribs.

2. A gas heat exchanger for absorption type refrigerating systems of the kind employing an inert gas, comprising a substantially horizontal tube, a substantially horizontal partition for dividing said tube into a passage for rich gas and a passage for weak gas, and U-shaped plates located obliquely with respect to the axis of said tube, the bases of said plates being secured to said partition, and the legs of said plates forming heat transmitting ribs, said ribs being split towards said partition so as to form longitudinally staggered heat transmitting surfaces.

' ALVAR. LENNING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,103,440 Sellon July 14, 1914 1,912,644 Lenning June 6, 1933 1,947,606 Lonergan Feb. 20, 1934 FOREIGN PATENTS Number Country Date 179,722 Germany Aug. 13, 1905 

